A few days ago was World hypertension day and a lot of awareness was being made. So, in commemoration of world hypertension day, I will be sharing this post on essential hypertension and ways to prevent it.
What is hypertension?
Hypertension is when the pressure in the blood is higher than what is regarded as normal. The pressure in the blood is dependent on the force in which the blood is leaving the heart and the size of the vessel. A small sized artery will offer more resistance compared to a large artery. This pressure acts on the wall of the vessel and over time the sequelae of its effect occur.
What values connotes high blood pressure?
There are different bodies with different values for hypertension. These professional bodies help with standardization and hence these values help with the management of patients.
According to the Joint National Conference 8, a systolic blood pressure of 140mmHg and diastolic blood pressure equal to or greater than 90mmhg is regarded as hypertension on 2 or more visits. The systolic blood pressure is the pressure of the blood when the heart contracts and pushes out blood while the diastolic blood pressure is the pressure when the heart is relaxing and receiving. This is why the systolic is usually higher than the diastolic. It is worthy to note that the number above is the systolic pressure and the number below is the diastolic pressure. So when next you visit a doctor you can understand the values.
What are the causes of hypertension?
The cause of hypertension in most cases is not known. This type of hypertension in which the cause is not known is called Primary hypertension or essential hypertension. It is so common that approximately 90% of all cases of hypertension are primary hypertension (AKA Essential hypertension).
10% of cases have a cause and hence this type of hypertension is called secondary hypertension. Secondary meaning it is secondary to a condition.
Although the causes of essential hypertension are not known, there are predisposing factors. These factors are things and conditions that increase the risk of acquiring a certain condition.
Age: As we age, the risk of having high blood pressure increases. This is why most people you know with hypertension are elderly people.
Race: Studies have shown that some ethnic group/ race are more susceptible. Some studies claim that African Americans are more prone to hypertension than any other race.
Sex: A study done in 2018 revealed that males have a higher risk of hypertension when compared to females. Although this is up until menopause. Studies also suggest that after menopause the risk of developing hypertension is equal in both genders. This might be due to the lack or reduced level of oestrogen after menopause.
Stress: Stress predisposes to a lot of conditions and hypertension is inclusive. Any type of stress can cause hypertension, be it physical, mental or emotional. You must have heard people say things like thinking can cause one’s blood pressure to rise, I guess they were trying to point out mental stress and not necessarily thinking.
Lack of exercise: Studies have shown that exercise has a beneficial effect in reducing blood pressure and helping in the pumping force of the heart.
Hormonal activities: Increase in the activities of some hormones tend to increase the likelihood of developing high blood pressure.
Diets have been observed to play a role. Diet rich in salt and fat have been seen to contribute to the development of hypertension.
The causes of secondary hypertension are specific and can be traced to the mechanism by which increased blood pressure develops. The causes of secondary hypertension include;
- Chronic Kidney disease
- Conn’s syndrome
- Diabetes ‘
- Cushing’s syndrome
How does hypertension develop?
By Juvo415 - Own work, CC BY-SA 4.0, Wikimedia
The body has an autoregulatory mechanism that regulates blood pressure. The autoregulatory mechanism is made up of the kidneys, the brain, the lungs and the adrenals. There is a system called the Renin-Angiotensin aldosterone system that is responsible for pressure regulation in the blood.
When there is reduced blood flow to the kidney, a part of the kidney called the juxtaglomerular apparatus secretes renin which enters the circulation.
Angiotensinogen is a protein that is produced by the liver. The secreted renin converts angiotensinogen to angiotensin 1. An enzyme called angiotensin-converting enzyme(ACE) is produced by the endothelium of the lungs. This enzyme acts on angiotensin 1 and converts it to angiotensin 2.
Angiotensin 2 has a variety of functions that contribute to the regulation of blood pressure. The effect of angiotensin 2 can be grouped into cardiovascular, neural, renal and adrenal cortex effect.
Angiotensin 2 acts on a certain receptor found in the endothelium of arterioles throughout the circulation to achieve vasoconstriction. This vasoconstriction is achieved through a series of biochemical reactions and the net effect of this constriction increases the total resistance offered by the vessels and ultimately results in an increase in blood pressure.
When there is an increase in absorption of water from the kidneys or there is reduced excretion of water, this result in an increase in pressure of the blood against the vessel.
It is worthy to note that when sodium is absorbed, it is absorbed alongside water.
Angiotensin 2 acts at the hypothalamus to stimulate the sensation of thirst, resulting in an increase in fluid consumption. This helps to raise the circulating volume and in turn, blood pressure.
Diuresis refers to an increase in the excretion of urine. Antidiuretic hormone prevents diuresis thereby resulting in a reduction in the excretion of urine.
Angiotensin 2 increases the secretion of Antidiuretic Hormone from the posterior pituitary gland resulting in the production of more concentrated urine to reduce the loss of fluid from urination. This in turn leads to a further increase in blood pressure as there is increased blood volume.
Angiotensin 2 also stimulates the sympathetic nervous system to increase the release of Noradrenaline. Noradrenaline is a hormone that is responsible for fight or flight response. This is the hormone that is activated when you see people running for no reason and all of a sudden you start running.
This hormone is also important in the RAAS system as it causes an increase in cardiac output, vasoconstriction and release of renin.
As earlier established Angiotensin 2 is a potent vasoconstrictor (i.e a substance that reduces the circumference of blood vessels). In the renal system, it causes vasoconstriction of vessels that carry blood in and out of the kidney leading to a reduction in the removal of fluid from the kidney.
It also causes absorption of sodium which is accompanied by water.
Any overactivity of these above processes results in an increase in blood pressure.
Finally, angiotensin 2 acts on the adrenal cortex to cause the release of aldosterone. Aldosterone is a hormone that acts on the kidney to cause sodium and water retention ultimately leading to an increase in blood pressure.
How can you identify someone that has hypertension?
Identifying or diagnosing hypertension is not such a herculean task. However, the problem with hypertension is that most times it has no symptom or sign that warns you. Hence, it is called a silent killer.
However, there are a lot of things that hypertension can present with if the signs are there.
Hypertension happens to be one of those conditions that can come with non-specific symptoms like a severe headache to specific ones like chest pain.
Some symptoms of hypertension include; chest pain, haematuria, difficulty in breathing, blurry vision, irregular heartbeat, nosebleeds, fatigue etc.
Sometimes a person might observe pounding in the neck, chest or ears.
I will explain how some of these symptoms come about in a subsequent post.
How can hypertension be prevented?
In as much as the knowledge of how hypertension comes about is important, much of the importance is in its prevention.
Prevention of hypertension starts from the following;
Health education: Educating the public about the dangers and importance of good health-seeking behaviour.
Regular blood pressure check: A lot of people in my country have not checked their blood pressure. This is partly due to ignorance and also poor health-seeking behaviour. This is why stroke and some conditions that are due to a sustained increase in blood pressure are on the rise in accident and emergency department in Nigeria.
Diet: Diet contributes a lot when it comes to the development of hypertension as being obese is associated with high blood pressure.
Exercise has many benefits and one of the benefits is a reduction in blood pressure. This is one reason why athletes have reduced blood pressure compared to the whole population.
Reduction in Alcohol intake: Alcohol has been observed to be notorious for causing liver damage. Some of the proteins involved in regulating the body mechanism are produced by the liver and this, in turn, could lead to hypertension.
Reduction in smoking: Smoking has been observed to be a risk factor for the development of hypertension. Asides from that smoking cigarettes have been associated with a variety of terminal conditions like lung cancer and chronic obstructive pulmonary disease(COPD). COPD has a direct relationship with hypertension and 90% of cases of COPD are due to smoking.
Adherence to drugs: There are some drugs that fall into the class of drugs to be taken for life when started. Notably, antihypertensive drugs are one of those drugs. A lot of people present to the hospital with hypertensive crisis to the emergency department and after questioning them, a percentage of them either stopped their drugs or didn't take it religiously.
When should you see a doctor?
Since hypertension is a silent condition then you should see your doctor once you have constant headaches, chest pain or once you start feeling the above symptoms persistently. You should also see a doctor when your blood pressure reading is consistently above 130/90 mmHg.
What are the complications of hypertension?
The major problem with hypertension is in its complication. The complication of hypertension can be very life-threatening and they include the following;
- Stroke: This is a very common neurological condition in which hypertension is a major risk factor. Stroke has also been identified as the top 3 leading cause of death worldwide.
- Blindness: This happens when the increased blood pressure affects the eye. This is known as hypertensive retinopathy.
- Glaucoma: This is the commonest cause of irreversible blindness. In this condition, there is increased intraocular pressure that is sometimes linked to increased blood pressure
- Heart failure: This is a condition where the heart fails to meet the physiologic demands of the body. If this condition is not managed properly, the mortality is as high as 80%
- Kidney damage
- Erectile dysfunction.
In conclusion, hypertension is a very common disease and early prevention and diagnosis will help promote favourable outcome. Lifestyle modification such as diet, exercise, cessation of alcohol and smoking reduces the chances of developing hypertension.
Thank you for reading and keep being healthy.